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Full text of "The Cambridge Natural History"

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phins and, especially,-Physeter. This asymmetry affects parti-
cularly the premaxillae, the maxillae, and the nasals. The
base of the skull is symmetrical. The Whale's skull has very
long premaxillae which, however,, do not, except in the extinct

FIG. 184.—Under surface of  the cranium  of   a young Caa'iiig Whale
melos). x &„ A&, Alisphenoid ; BO, basioccipital ; c/", condylar foramen ; JSrO,
exoccipital j JPV, supra-orbital process of frontal; £/", glenoid fossa of squaruosal;
JMa, body of malar ; MX, maxilla ; 0JS> orbitosphenoid ; Per* posterior (mastoid)
process of periotie ; PI, palatine ; PMx, premaxilla ; Pi*, pterygoid ; Sq, sqnamosal j
tg, deep groove on squamosal for meatus auditorius exteruxis, leading to tympanic
cavity; Ty, tympanic ; Fo, vomer; 2Mt zygomatic process of malar. (From
Mower's Osteology.)
Zeuglodonts, bear any teeth. The nasal bones, whether sym-
metrical or the reverse, are very small in existing "Whales,
which arrangement, together with the long and broad maxillary
bones, removes the anterior nostrils, the blow-hole, far back-
wards. The roof of the skull is not at all formed by the
|jarietals externally. These bones form a portion of the side
of t&» cranium, but are replaced or covered by the enormously-